The operator's compartment of a conventional tractor or the like is normally equipped with a structure such as a roll-over protective structure, an environmental cab or a windshield. The installation or replacement of such a structure normally requires complete removal of the original operator's station, including its associated operator's controls for the tractor, and a complete reworking thereof or a replacement therefor. Such procedure is time consuming and costly and does not always provide the operator's compartment with a high degree of structural integrity and operator safety. In addition, a conventional operator's compartment is normally structurally integrated into the framework of a vehicle by welds and the like, thus making it difficult to remove the same should such become necessary.